Sound output works only via one of the two sound connections. Either the 3.5mm AUX or USB Type-C. Simultaneous operation of two headsets is not possible.

This active adapter differs from normal / passive adapters, as it has a built-in D/A controller and amplifier integrated inside the plug. As soon as a smartphone doesn’t support an analogue signal on its USB Type-C port, this external D/A controller and amplifier is required for audio output. Because of that 4smarts recommends choosing an active adapter like this, to ensure functionality in any way, no matter if the smartphone supports above mentioned output or not.